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 Table of Contents  
CASE REPORT
Year : 2018  |  Volume : 9  |  Issue : 2  |  Page : 91-95

An innovative technique for fabricating a mirror image wax pattern using three-dimensional printing technology for an auricular prosthesis


Department of Prosthodontics, Vasantdada Patil Dental College, Sangli, Maharashtra, India

Date of Web Publication18-Jun-2018

Correspondence Address:
Rohit Vijay Sanghavi
8, Shivdutta Apt, Khatri Estate, Baramati - 413 102, Pune, Maharashtra
India
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DOI: 10.4103/srmjrds.srmjrds_7_18

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  Abstract 

Congenital microtia is a major anomaly of the external ear. Ear prosthesis is considered to be one of the most difficult replacements in maxillofacial reconstruction. The convolutions and severe undercuts in the ear present the challenge in simulating exact normal ear contours. The advent of digital technology in maxillofacial prosthesis has allowed fabrication of exact anatomical models. Fabrication of mirror image remains the challenge as the conventional technique depends on the skills of the technician. The purpose of this article is to describe an innovative technique for fabricating a mirror image in constructing an auricular prosthesis.

Keywords: Mirror image, stereolithography, three-dimensional printing


How to cite this article:
Sanghavi RV, Shingote SD, Abhang TN, Thorat PR, Vathare AS. An innovative technique for fabricating a mirror image wax pattern using three-dimensional printing technology for an auricular prosthesis. SRM J Res Dent Sci 2018;9:91-5

How to cite this URL:
Sanghavi RV, Shingote SD, Abhang TN, Thorat PR, Vathare AS. An innovative technique for fabricating a mirror image wax pattern using three-dimensional printing technology for an auricular prosthesis. SRM J Res Dent Sci [serial online] 2018 [cited 2021 Apr 15];9:91-5. Available from: https://www.srmjrds.in/text.asp?2018/9/2/91/234594


  Introduction Top


Auricular defects may be acquired or congenital and are the second most common craniofacial malformations after cleft lip and palate.[1] With congenital defects such as microtia, where one ear is missing, existing facial asymmetry presents difficulty in determining the size and location of an artificial ear that will maintain facial harmony.[2],[3]

Several techniques have been reported to fabricate a mirror image wax cast for maxillofacial prostheses. However, the success of prosthesis depends on the maxillofacial technician's skill and artistry. The advent of computed tomography (CT) scanning and three-dimensional (3D) printing technology in rehabilitation of maxillofacial defects facilitates the fabrication of facial prosthesis more accurately and precisely.[4],[5],[6]

The purpose of this article is to present a new technique for creating a mirror image wax pattern for fabrication of auricular prosthesis using 3D printing technology.


  Case Report Top


A 19-year-old male patient reported to the department of prosthodontics with a chief complaint of malformed right ear which was congenitally malformed [Figure 1].
Figure 1: Congenital ear defect

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The patient was concerned about his disfigured look due to malformed ear and wanted it to be corrected. A thorough examination of the affected area was done. Only some part of helix and tragus was present. Hearing ability was absent with right ear. Patient's left ear was normal with normal hearing ability and was used as a guide for the fabrication of wax pattern for the missing ear.

Impression procedure

Impression was made with the patient lying in a supine position. Horizontal and vertical lines were marked through the external auditory meatus on both defective and nondefective side for proper orientation of prosthesis [Figure 2]. Irreversible hydrocolloid material was used to make an impression. A backing of quick setting plaster was used to stabilize and support the impression. The impression was beaded and boxed and poured in dental stone [Figure 3] and [Figure 4]. The same procedure was done on defective and nondefective sides.
Figure 2: Impression making of defective side

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Figure 3: Model of defective side

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Figure 4: Model of contralateral side

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Mirror image fabrication

Cast of contralateral ear was used to fabricate a mirror image [Figure 5]. The cast was scanned using a spiral CT scanning system. Several slices of 1.25 mm thickness were generated and a volumetric model was created. These files were converted to STL format, which represented the surface geometry as a polygon mesh. This digitized model was imported into the Free Form Software System (SensAble Technologies) and a mirror image was obtained using the software [Figure 6]. A virtual model of the required prosthesis, with the mirrored digital image, was adapted to the defective side image. A prototype of the desired prosthesis was obtained.[2],[7]
Figure 5: Scanned image of contralateral side

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Figure 6: Mirror image fabrication

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Fabrication of model wax ear

3D printing technology (Stereolithography) was used to fabricate the model ear. The obtained digitized data were traced out by a laser beam onto an acrylic photopolymeric, and an ear model was fabricated [Figure 7] and [Figure 8]. The impression of the obtained acrylic ear prosthesis was made using addition silicone impression material. The impression was poured in hot wax, and a wax pattern of the defective side was obtained.[7]
Figure 7: Fabrication of resin mold by three-dimensional printing technology

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Figure 8: Rear View of 3D Printed Mould

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Wax pattern trial, shade matching, and three-piece mold fabrication

The duplicated wax pattern was verified on the patient and verified with the normal ear to ensure symmetry, orientation, and visibility [Figure 9]. Shade matching was done in several parts of normal ear to get exact shade of contralateral ear and achieve good esthetic results [Figure 10]. A three-piece mold technique was used to flask the wax ear [Figure 11]. Room temperature vulcanized silicone (RTV) was used to pack the mold.
Figure 9: Wax try-in of ear prosthesis

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Figure 10: Shade matching

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Figure 11: Fabrication of three-piece mold

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After 48 h of curing at room temperature, mold was disassembled, and silicone form was retrieved. The retrieved prosthesis was externally characterized and finished [Figure 12] and [Figure 13].
Figure 12: Preoperative

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Figure 13: Postoperative

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Retention and maintenance

After finishing of the ear prosthesis, it was retained over the defect surface with the use of bioadhesive and the undercuts present in the defect.

The patient was instructed to keep the skin surface clean to ensure proper adhesion prosthesis and also to remove the prosthesis at night to avoid excessive forces on the prosthesis while sleeping.


  Discussion Top


The fabrication of ear prosthesis is considered to be one of the most difficult replacements in maxillofacial reconstruction. Various techniques have been used to fabricate wax patterns of auricular prostheses. Most are difficult and time-consuming and rely on a high level of artistic ability.[8] Coward et al.[2] described a technique of fabricating wax pattern for auricular prosthesis using stereolithography. Sykes et al.[7] described the applications of rapid prototyping technology in maxillofacial prosthetics and scanned the contralateral ear cast for fabrication of ear prosthesis. The technique used in the present article is a combination of the above-mentioned two techniques. Cast of the contralateral ear was scanned because CT scanning that is used only to create a mirror image is not ethically justified because of the dose of radiation.[2]

The 3D-printed ear model was preserved and duplicated so as to overcome the disadvantages of the RTV silicone which include poor color stability, tear strength, and poor dimensional stability.[9] The preserved 3D-printed ear model will allow to fabricate the ear prosthesis multiple times without the need of any extra impression or scanning procedures and thereby reducing the cost of the prosthesis. This technique enables the prosthodontist to fabricate the ear prosthesis with great accuracy and is also an economic solution to the conventional 3D printing techniques.

However, there were some limitations in the use of this technique. The conventional duplication process which was used in this technique involves many steps during which errors can occur. The distortion of wax can occur during the duplication of mold which can hamper the accuracy and esthetics of the prosthesis.[2]


  Conclusion Top


Current techniques available for the fabrication of wax ears require the maxillofacial technician to spend time carving and adapting the ear to cast of the deficient side of the face. These techniques rely on the skill and individual ability of the technician. The technique used in this article produces a wax ear model of the same shape, internal contouring, and dimensions as the opposite ear with the added advantage of that the ear fits the appropriate position on the soft-tissue contours of the deformed side of the face.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgment

We would like to acknowledge our institution, Vasantdada Patil Dental College and Hospital, Kavalapur, Sangli and all the teaching staff of the department of prosthodontics for their timely suggestions.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Jiao T, Zhang F, Huang X, Wang C. Design and fabrication of auricular prostheses by CAD/CAM system. Int J Prosthodont 2004;17:460-3.  Back to cited text no. 1
[PUBMED]    
2.
Coward TJ, Watson RM, Wilkinson IC. Fabrication of a wax ear by rapid-process modeling using stereolithography. Int J Prosthodont 1999;12:20-7.  Back to cited text no. 2
[PUBMED]    
3.
Mittal N, Hegde R, Karla A, Manmohit S, Banhot S, Fahim R. Prosthetic ear fabrication using a customized three piece mould: A case report. Indian J Dent Sci 2013;4:93-5.  Back to cited text no. 3
    
4.
Ciocca L, Roberto M, Gassino G, Scotti R. CAD/CAM Ear model and virtual construction of the mold. J Prosthet Dent 2007;98:339-43.  Back to cited text no. 4
    
5.
Coward TJ, Scott BJ, Watson RM, Richards R. A comparison of prosthetic ear models created from data captured by computerized tomography, magnetic resonance imaging, and laser scanning. Int J Prosthodont 2007;20:275-85.  Back to cited text no. 5
[PUBMED]    
6.
Wang S, Leng X, Zheng Y, Zhang D, Wu G. Prosthesis-guided implant restoration of an auricular defect using computed tomography and 3-dimensional photographic imaging technologies: A clinical report. J Prosthet Dent 2014;1:1-4.  Back to cited text no. 6
    
7.
Sykes LM, Parrott AM, Owen CP, Snaddon DR. Applications of rapid prototyping technology in maxillofacial prosthetics. Int J Prosthodont 2004;17:454-9.  Back to cited text no. 7
[PUBMED]    
8.
Thotapalli S. Fabrication of mirror image prosthetic ears – A short review. Anaplastology 2013;2:120-3.  Back to cited text no. 8
    
9.
Barhate AR, Gangadhar SA, Bhandari AJ, Joshi AD. Materials used in maxillofacial prosthesis: A review. Pravara Med Rev 2015;7:5-8.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13]


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